1. Field of the Invention
This invention relates to an image forming apparatus included in an electrophotographic system such as a copying machine, a printer, a facsimile apparatus and the like. More particularly, the present invention relates to an image forming apparatus including a developing apparatus in which two-component developer or one-component developer is used as is a toner supplying apparatus for supplying toner to a developing section of the developing apparatus.
Furthermore, the present invention relates to an image forming apparatus having a toner delivering apparatus for delivering toner in a way such that the toner may be reused or discarded.
2. Discussion of the Background
Selected conventional image forming devices include a toner delivering apparatus in which toner remaining on a photosensitive body is recovered by a photosensitive body cleaning apparatus and then delivered to a developing apparatus so as to be reused. This type of apparatus is equipped with a toner transmitting mechanism A and a powder pump B, for example, as shown in FIGS. 48 and 49. If toner recovered by the photosensitive body cleaning apparatus 501 (FIG. 48) is reused, the recovered toner is then discharged from a discharging tube 501a of the body cleaning apparatus 501, as shown in FIGS. 48 and 49, and is dropped into a transfer guide case 502 via a connection case 503. All the while, a rotation of a driving motor causes a horizontal delivery screw 504 to rotate in the transfer guide case 502. The screw 504 rotates integrally with a rotor 507 in a stator 506 of the powder pump B, so that the recovered toner is transmitted into the stator 506 through a rotation of the horizontal delivery screw 504.
Furthermore, the toner is pressed out, by the rotation of the rotor 507, through the toner outlet 505 from an inside of the stator 506 into a toner transfer pipe 508 connected to a toner outlet 505a, and air is blown into the powder pump B via an air transfer pipe 509a by an air pump 509 so as to be transmitted into the toner transfer pipe 508. The toner passing through the toner transfer pipe 508 is thus moved along via an air flow so as to be delivered to the developing apparatus.
In addition, in an image forming apparatus in an electrophotographic system such as a copying machine, a printer, and a facsimile, a developing apparatus contained therein makes visible a static latent image formed on a latent image carrier such as a photosensitive body by supplying toner thereto. The developer is supplied so as to maintain an image density if two-component developer or one-component developer is consumed as a result of making previous images. As part of the new developer, toner is generally used, and a toner supplying apparatus used for supplying the toner is, for example, disclosed in Japanese Unexamined Patent Publication No. 2-277083.
As shown in FIG. 50, the toner supplying apparatus disclosed in the above patent publication includes a toner tank 521 for storing toner supplied to a developing section 522 arranged near a photosensitive body 541, a toner residue detector (i.e., a toner sensor) 523 for detecting residue of toner in the toner tank 521, and a toner server 524 for supplying toner to the toner tank 521 arranged so as to be adjacent to the toner tank 521. The toner server 524 includes a toner server body 525, a rotating member 526 having a number of extending portions which radially extend therefrom and are spaced nearly equally apart from one another in a circumferential direction and being rotatably supported by the toner server body 525, a plurality of cartridge supporting member 527 supported so as to be rotatably movable at a tip of each of said extending portions, a plurality of toner cartridges 528 containing toner removably installed in each cartridge supporting member 527, a first driving motor 529 for rotating the rotating member 526, and a second driving motor 530 for rotating the cartridge supporting members 527, in which the first and second driving motors are controlled to be driven by a controlling mechanism 531 based on a result of a detection obtained by the toner residue detector 523. The toner supplying apparatus having the above configuration is characterized by that, when the rotating member 526 and the cartridge supporting member 527 rotate or rotatably move and then stop at a fixed position, an opening portion so as the toner cartridge 528 for discharging toner is opposed on the top surface of the toner tank 521 by each toner cartridge 528 falling down and then toner contained in the cartridge is made to fall out from the opening portion so as to supply the toner to the toner tank 521.
According to the above described toner supplying apparatus, the toner server 524 has a plurality of toner cartridges 528 and the toner cartridges 528 are automatically displaced in a circumferential direction a specific number of times, so that a frequency with which the toner cartridge 528 must be exchanged is decreased.
In addition, in the above described conventional toner supplying apparatus, the toner sensor 523 is used for detecting a residual amount of toner in the toner tank 521 which is a toner collecting section, after toner being supplied from each toner cartridge 528, but not used for detecting the amount of residual toner in each toner cartridge 528. Accordingly, when the toner sensor 523 indicates a toner end, every toner cartridge 528 in the toner server 524 must be empty. Moreover, when the toner sensor 523 detects the toner end, there is no toner in the image forming apparatus and therefore the image forming apparatus cannot continue an image forming operation without being halted so that more toner can be added thereto.
Further, the toner server 524 has a sealed structure. Also from this viewpoint, the conventional devices has a configuration in which toner cartridge cannot be exchanged while the image forming apparatus continues to operate. As described above, there is a problem that the image forming apparatus must be temporality stopped for replacing a toner containing member such as a toner cartridge when supplying toner in the conventional image forming apparatus.
Furthermore, in another conventional technology, there is a toner supplying apparatus which includes a toner tank for storing toner to be supplied to a developing section, a toner residue detecting sensor for detecting residue of toner in the toner tank, and a toner bottle for supplying toner to the toner tank, arranged so as to be adjacent to the toner tank. Although the toner bottle must be replaced by new toner bottle when empty, it is known that there is a toner supplying apparatus having more than one toner bottle so that an exchanging frequency of the toner bottles can be decreased. This type of a toner supplying apparatus discharges toner from a toner bottle to a toner tank by an appropriate amount by using a known approach, and if a toner residue detecting sensor detects a reduction of the toner residue in the toner tank, it determines that the toner bottle is empty and starts to use another new toner bottle.
As recognized by the present inventors, in the above conventional toner delivering apparatus, there is provided a thin toner outlet 505a (FIG. 48) in a tip side of the pump case 505 as described above so that the toner transfer pipe 508 having a relatively small diameter can be connected to the powder pump B. However, this approach has a problem in that heat generated by friction is easily generated between the stator 506 and the rotor 507 during delivering toner in the powder pump B, whereby the toner is aggregated with an effect of frictional heat being generated and the aggregated toner remaining therein when attempting to pass through the narrow toner outlet 505a, and ultimately the outlet 505a becomes clogged.
Furthermore, in a developing apparatus of the conventional image forming apparatus, the present inventors have recognized problems in that a large amount of toner storage (containing amount) makes the configuration of the developing apparatus larger than desired because a toner storage section and a developing apparatus are integrally configured. As a consequence, the conventional configuration of the image forming apparatus is more complicated than necessary, and reduces operability and ease of maintenance of the apparatus. Additionally, a layout of the body of the conventional apparatus is restricted by these problems and therefore it also causes a problem that a larger area is required for hosting the apparatus. For example, also in a case of the above toner supplying apparatus, the toner server for supplying toner to the toner tank in the developing apparatus is arranged so as to be adjacent to the developing apparatus and its arrangement position is restricted, whereby it cannot avoid the problems associated with having a complicated apparatus configuration, a larger size, and restricted component layout.
Further, the above described problems of the conventional toner supplying apparatus cause an increase in apparatus down-time, and thus increase copying or printing cost for a user who copies or prints a large amount of data. Naturally, in apparatuses with a large capacity toner supply, the apparatus that delivers the toner must be reliable. However, conventional system achieve higher reliability by using larger systems at great expense, but such systems are not practical in small, lower cost systems that require low power consumption and simple toner delivery mechanisms.
According to conventional wisdom in devices in which a plurality of toner cartridges are circumferentially rotated so as to be moved while being sequentially directed toward predetermined positions (e.g., such as in the toner supplying apparatus disclosed in the above discussed patent publication), a structure for enabling a movement of the cartridges is indispensable. However, as recognized by the present inventors, this approach leads to an increase in a size of the apparatus. In addition, a body of the toner server must reserve a sufficient amount of toner by containing a plurality of toner cartridges and therefore it requires a larger volume than that required to host the toner cartridges themselves.
To supply toner from one of the toner cartridges, the toner cartridges must be moved. Additionally, the toner cartridge to be moved must be filled with toner inside. Therefore, when toner is supplied from the toner cartridge, a particular sequence of cartridges must be selected and is not practical to select the cartridges in an arbitrary manner.
In the toner supplying apparatus disclosed in the above discussed patent publication, toner is discharged when the toner cartridge, which has arrived at the position where toner is to be supplied, falls down over top of a toner tank. In this configuration, however, if the toner cartridge is attempted to be replaced when in a position where the cartridge can spill toner and create a mess, the toner cartridge must be moved again to another position where toner will not spill from the toner cartridge. Accordingly, replacing toner cartridges is a challenge for an operator.
Furthermore, if a toner cartridge in a toner bottle configuration is simply enlarged, the toner supplying apparatus becomes larger and the amount of space allocated for the toner supplying apparatus is restricted. Thus, this is yet another reason why a cartridge in the conventional apparatus results in undesirable down-times.
If it is determined that a toner bottle is empty by using a sensor for detecting toner residue in a toner tank like the above toner supplying apparatus, there is a problem regarding how precisely the sensor can act based on a variability of a sensitivity of the sensor or a speed of discharging toner from the toner bottle. If a bottle is misinterpreted as being empty, a subsequent toner bottle must be used wastefully though toner still remains in the first toner bottle. Further, if a toner discharging aperture of the toner bottle which becomes empty is opened when exchanging the toner bottle, toner in the toner bottle is scattered, whereby a peripheral portion is contaminated undesirably. Still further, in a toner supplying apparatus of a type in which a capped toner bottle is automatically uncapped with the cap being held when the toner bottle is started to be used, there is a disadvantage that, if it is forgotten to be replaced, the removed cap from the empty toner bottle prevents a cap from the new toner bottle from being removed.
In addition, as disadvantages of an image forming apparatus equipped with a conventional large-volume toner tank, there have been the following problems, as recognized by the present inventors:
1) It is difficult to supply toner to the toner tank, and thus, is not user-friendly; and PA1 2) Since toner blocking in the toner tank (due to compressed toner at the bottom) occurs, a mechanism for preventing this blocking is required.